This invention relates to carburetors for internal combustion engines and, more particularly, to automatic choke control mechanisms for such carburetors.
In one type of prior art automatic choke control mechanisms for internal combustion engine carburetors, the choke valve is controlled in response to temperature by a thermostatic element and is initially opened in response to engine suction pressure by a vacuum diaphragm assembly connected in communication with the engine intake manifold. In another type, the choke valve is controlled solely by a vacuum diaphragm assembly connected in communication with the engine intake manifold or with the carburetor induction passage upstream of the throttle valve. The latter type of automatic choke control mechanism generally is not effective for many engines which, at higher speeds, do not produce a suction pressure sufficiently low enough for the vacuum diaphragm assembly to maintain the choke valve in an open position.
Examples of these types of automatic choke control mechanisms are disclosed in the following U.S. Pat. Nos.:
Hill, 3,085,792, issued Apr. 16, 1963;
Lechtenberg, et al., 3,194,224, issued July 13, 1965;
Lucas et al. 3,272,486, issued Sept. 13, 1966;
Jones, 3,484,220 issued Dec. 16, 1969;
Reichenbach, et al. 3,625,492 issued Dec. 7, 1971;